Many types of reusable drinking devices designed to limit accidental spilling are known. These cups have three general goals that are in significant tension with each other. One is to allow a user to readily intentionally drink a liquid. The second is to limit the flow rate or total volume of liquid emanated in the case of a non-drinking situation. For example, on occasions when the vessel is being dropped, thrown or is otherwise not upright and stable it is desirable to minimize spillage. In a reusable device, a third goal is confident cleanability, preferably with little risk of loosing various small parts. Many spill resistant designs feature constricted passageways and small spout and air vent openings. Some designs have slit valves. These characteristics can lead to cups that are difficult to clean compared with household food preparing and serving items generally. Cleanability issues are amplified by the general problems of cleaning milk and the heightened concern for cleanliness a parent might have for their child's drinking devices.
Designs with sophisticated valves may also have the deficiencies of complexity and of small parts that can be easy to lose. Those without valve mechanisms generally are either too hard to extract liquid from while drinking or too easy to spill liquid from when shaken or tipped over. Although many diverse designs are known there is nevertheless a need for a solution that allows drinking without undue effort yet limits spillage under real-world use conditions. It should also be as readily cleanable as most other food serving items.